EFFECT OF TRYPSIN-DIGESTED BOVINE GROWTH HORMONE ON WHOLE-BODY PROTEIN SYNTHESIS IN VITRO IN CHICKEN EMBRYOS

The effect of bovine growth hormone digested with trypsin on whole-body protein synthesis in vitro of chicken embryos was investigated by using a whole-embryo culture system. Bovine growth hormone at 5.3 and 530 ng/ml was digested partially and completely with trypsin for 4 min and 18 h, respectively. After culturing chicken embryos with a synthetic medium containing $L-[4-^3H]$ pheylalanine, whole-embryo protein synthesis was determined from the ratio of specific radioactivities of free and protein-bound pheylalanine. Whole-embryo protein synthesis of the control group cultured with no bovine growth hormone was $49.5{\pm}2.2%/d$. There was no significant interaction between digestion time and the concentration of trypsin-digested bovine growth hormone. Tryptic digestion of bovine growth hormone increased fractional synthesis rates of whole-body protein compared to the 0-min groups, and there was no significant difference between the 4-min and 18-h groups. The higher concentration (530 ng/ml) of trypsin-digested bovine growth hormone was more effective in enhancing whole-embryo protein synthesis than the lower concentration (5.3 ng/ml).